As time passes Axiom does make changes, only they could give you a factual answer to the question... It was possible the specs on site are current with production of today's V3's. Based on what you have posted, your speakers are more efficient by 3dB's, however the site drops the freq response down 3Hz. In reality not much to worry about and most likely not audible to the user, especially if you are using a crossover.

Xavier, welcome. Quite some time ago both Randy and I commented on a sudden 3 or 4dB increase in the sensitivity specs of several models(not including the M80). Axiom didn't clarify the situation. The present decrease in the M80 spec raises the same question. The present sensitivities shown here indicate that the M50 and M60 are now significantly more sensitive than the M80, which seems unlikely.

Axiom should clarify if these measurements are under different conditions(and therefore not useful for comparisons), rather than indicating a significant change in the actual sensitivities.

Seems the site and what's on the speakers is off in general. The serial numbers on my speaker boxes claim my M100's are 8 ohm speakers while the site says 4 ohms. They also claim they're M100 v3. Seems these would be v1 as they're a new model. Likely left overs from the M80 entry in the system since it seems the box spacers are the same. Not sure what the 8 ohms is from though.